Samuel E. Ogbeide

Biocrude Production through Pyrolysis of Used Tyres

A review of the pyrolysis process of used tyre as a method of producing an alternative energy source is presented in this paper. The study reports the characteristics of used tyre materials and methods of recycling, types and principles of pyrolysis, the pyrolysis products and their composition, effects of process parameters, and kinetic models applied to pyrolysis. From publications, the proximate analysis of tyre rubber shows that it is composed of about 28.6 wt.% fixed carbon, 62 wt.% volatile material, 8.5 wt.% ash, and 0.9 wt.% moisture. Elemental analysis reveals that tyre rubber has an estimated value of 82 wt.% of C, 8 wt.% of H, 0.4 wt.% of N, 1.3 wt.% of S, 2.4 wt.% of O, and 5.9 wt.% of ash. Thermogravimetry analysis confirms that the pyrolysis of used tyre at atmospheric pressure commences at 250°C and completes at 550°C. The three primary products obtained from used tyre pyrolysis are solid residue (around 36 wt.%), liquid fraction or biocrude (around 55 wt.%), and gas fraction (around 9 wt.%). Although there is variation in the value of kinetic parameters obtained by different authors from the kinetic modeling of used tyre, the process is generally accepted as a first order reaction based on Arrhenius theory.

Adsorption and Desorption Kinetics of Naphthalene, Anthracene, and Pyrene in Soil Matrix

Abstract The adsorption and desorption kinetics of naphthalene, anthracene, and pyrene in a soil slurry reactor at ambient conditions have been investigated to ascertain the mechanisms controlling the retention and release rates of these compounds in the soil matrix. A stirred-flow method was employed to perform the experiments. The extent of partitioning for the polycyclic aromatic hydrocarbons (PAHs) tested was found to be dependent on their solubility and diffusivity in the aqueous phase. Apparent adsorption and desorption rate coefficients were determined using the Langmuir and Freundlich isotherm models. Equilibrium adsorption and desorption at the external surface and in the internal pore of the soil particle obeyed the Freundlich isotherm equation. The pseudo-equilibrium condition established at the minimum contact time suggests that equilibrium adsorption attained for the contaminant PAHs was not instantaneous but rather time dependent.

Substrate Bioavailability on the Biodegradation of Recalcitrant Polycyclic Aromatic Hydrocarbons in Aqueous-Sediment Matrix: A Mini Review

The increased quest for technology and industrialization by a dynamic society, where the fuel requirements of the energy sector and the chemical and petrochemical needs of the chemical and allied industries are satisfied, is greatly dependent on the petroleum industry in which the downstream sector is a key player. These needs range from the feedstock requirements of the chemical industries, polymeric industrial sector, solvent sector, cosmetics industries, etc. The downstream environment has over time been subjected to a barrage of sustained and unmitigated pollution of its air, land, and sea by polycyclic aromatic hydrocarbons. The frequency of discharge of petroleum and petroleum products into the environment, particularly land, and their build-up, compromises the quality of the environment. Generally, the discharge of these groups of compounds into the environment, whether accidental or intentional, has adverse ecological effect in oil-producing areas of the world. These effects, apart from the degradation of the ecosystem, also results in commodity loss, loss to the communities that depend on such lands for their livelihood, and economic loss due to spill clean-up cost. The development of effective clean-up technology to reduce the levels of these hydrocarbon contaminants in order to meet environmental regulation standards is thus a continuing subject of research.

Evaluation of pyrolytic oil from used tires and natural rubber (Hevea brasiliensis)

ABSTRACT The pyrolysis of used tires, UT, and natural rubber (Hevea brasiliensis), NR obtained from Nigerian NIG800 clonal rubber tree, was performed and the effects of process conditions on product yield were investigated. An optimum yield was attained at operating temperature of 600°C, a heating rate of 15°C min−1, for a feed size of 6 mm. The UT and NR gave maximum pyrolytic oil yield of 34.40 and 75.93 wt%, respectively. The pyrolytic oil was characterized using Fourier transform infrared, nuclear magnetic resonance, and gas chromatography–mass spectrometry (GC–MS). Results obtained reveal the pyrolytic oil to be a complex mixture, mainly of aliphatic and aromatic compounds, which can serve as feedstock for industrial application. Nevertheless, a comparative evaluation of the physical and chemical properties of the UT and NR pyrolytic oil showed that NR had hydrocarbon composition of 80% aliphatics, 12% aromatics (with less than 2% polycyclic aromatic hydrocarbon concentration). However, the UT pyrolytic oil had 42% aliphatic and 34% aromatic compounds (with polycyclic aromatic hydrocarbons concentrations of 18%). Also, NR pyrolytic oil had better physical properties such as density, viscosity, flash point, pour point, and higher heating value than that produced from UT in this study, and comparable with that of commercial diesel. Moreover, sulfur content, which is a limiting factor in the direct combustion of UT pyrolytic liquid, was absent in NR pyrolytic oil. Hence, it is technologically feasible for NR from H. brasiliensis to be a suitable source of pyrolytic oil than UT.

Linear and nonlinear kinetic modelling of the uptake rate of aromatic hydrocarbons in aqueous-sediment matrix

The time-dependent adsorption data of naphthalene, anthracene and pyrene onto sandy soil fraction conducted at a constant temperature of 25°C which represents environmental condition has been investigated using linear and nonlinear kinetic modelling approaches. Experimental data were analysed using four kinetic models; pseudo-first order, pseudo-second order, intraparticle diffusion and Elovich model equations. In order to gain insights into the mechanism controlling the sorbate-sorbent system as well as to determine the best fitting model, the correlation coefficients, and standard error estimates were used for analysis. Results of the equilibrium rate constant, adsorption capacity and correlation coefficients obtained from the different kinetic models showed that the nonlinear approach had reasonably better fits to the experimental data. This was affirmed by the use of standard error estimates. Of all the nonlinear models used the pseudo-first order kinetics successfully predicted the adsorption of the contaminant solutes. Overall, the results demonstrate that linear modelling approach is not suitable for describing the uptake of these contaminant solutes onto sediment fractions being characterised by poor regression coefficients and high standard error measurements and hence not applicable to this study.

A Comparative Study of Different Kinetic Lumps Models in the Fluid Catalytic Cracking Unit Using COMSOL Multiphysics

The COMSOL Multiphysics computational fluid dynamics software was used to simulate the fluid catalytic cracking (FCC) riser reactor of the FCC unit. The 4-, 5-, 10-, 20-, and 35-lump kinetic models were used to describe the kinetics of the cracking reactions in the riser reactor. The results of the kinetic lump models of the distributions of pressure, velocity, temperature, and yields of products were compared using practical values from the Port Harcourt Refinery Company plant. The results showed that the higher the kinetic lumps the better the accuracy of the prediction of the product yields and that the 10-, 20-, and 35-lump kinetic models could be used to predict the yield of various fractions of the riser reactor using COMSOL Multiphysics.

Growth kinetics of some subsurface microbial strains using naphthalene as a probe contaminant.

The focus of this study is the unravelling of the microbial dynamics of the biodegradation of naphthalene, a polycyclic aromatic hydrocarbon, in an aqueous–sediment matrix. The Pour plate procedure was adopted for the isolation of the microbial colonies, while the sub‐culturing of the isolates was based on their cultural (biochemical) and morphological characteristics. Investigations showed that the microbial colonies consisted of the bacterial and fungal strains. The logarithmic growth curve was characterized by an initial lag phase, a rapid and exponential increase in cell biomass, a stationary phase and finally a death phase. Both strains in the presence of naphthalene‐impacted basal salt medium demonstrated that the microbial growth results in an almost linear increase in biomass concentration – an indication that mass transfer from the solid phase to the liquid phase (lag phase) is limiting for growth. The kinetics of the utilization of naphthalene expressed as the growth and consumption rates indicated that all the microbial strains isolated from an indigenous soil used in this study exhibited a high metabolic affinity for naphthalene. Optimal performance was demonstrated by the bacterial strains that could use naphthalene as their sole carbon and energy source.